Expanding brake



@0L my 3933- G. T, sMnH-CLARKE 1,930,47

EXPANDING BRAKE Filed Nov. 18, 1951 Patented Oct. 10, 1933 lUNH-13DSTATES EXPANDING BRAKE George Thomas smith-Clarkao'ventry, Eng-r land,assignor to The Alvis Car & Engineering K Company Limited, Coventry,England Application'November 18,1931, serial N0.575,875, and in GreatBritain-December 6, 1,930

9 claims. (ci. 18s-78),"

This invention relates to brakes which are nonservo (or notself-applying) of the kind having two shoes pivoted ona support andadapted to be'expanded by means of a `doating cam integral or xedlyattached'to its actuating lever.

According to this invention, the actuating lever -is accommodated in arecess in one of the shoes. Preferably the lever is arranged centrallyof the width of the shoe and the operating rod or cable therefor isledangularly out of theplane of the brake.

` (In, the accompanying drawing,

Figurel is a longitudinal vertical elevation of a brake drum` and brakeshoes adapted according to the invention, the anchor plate and someassociated parts being removed but indicated by chain liners; a Y -v vFigure 2VA is a horizontal section thereof ,taken substantially on theline II-II of Figure l;

Figure 3 is a vertical cross-section of one of the brake shoes and thelever-operated cam taken substantially on the line III-III of Figure 1;whilst Y Figure 4 is an end View taken' from the right of Figure 1 witha part of the brake drum shown in section and a part of the anchor plateshown broken away.

In the arrangement illustrated, the means for securing the brake drum 2upon the supporting hub (not shown) are omitted, asare also the means bywhich the anchor plate 3 is to be supported, these being well known inthe art.

There are shown, however, two brake shoes 4, 5 supported upon pivot pins6, 6 secured to the anchor plate, the brake shoes having a known form oflining 7, 7 to engage the internal periphery of the brake drum. The pins8, 8 secured to the anchor plate operate in elongated slots 9, 9 in theshoes and spring washers 8a held on the pins against opposite sides ofthe shoes serve to locate them for movement about their pivotal axes.

In the present instance the cam is shown as comprising two studs l0, llextending transversely from a disc l2 which'is co-planar withV theVlongitudinal centre-lines of the brake shoes. One of these studs l0lies within a substantially heini-cylindrical recess 13 Vformed in theface of the shoe 4 and the other shoe has a straight face 14 whichengages both the studs when the cam is in its fully oli position, asindicated in Figure 1. A take-oil spring 15 operates between the lugs16, 16 formed on the shoes, and by this means the stud l0 is held inposition between the co-operatingiaces of the brake shoes and the camthus floatingly anchored.

The disc 12 is formed integrally with an actuating lever 17 disposedmainly within a recess v 18 formed in the'brake shoe 4. The free end of60 the lever is shaped as a stirrup 19 the crosspiece of which issecured to the end 20 of the flexible cable 21. The casing 22 for thelatter is carried by an abutment 23 supported from the anchor plate, andit is bentV as shown at v24 and passed 65 Athrough an inclined hole2'5'in the anchor plate.

YThus, ithe iloating cam and actuating lever therefor are located'partly within one of the brake shoes and alsowithn the plane of thebrake shoes,` and the whole apparatus is contained within 'the brakedrum. y

It -is assumed that the direction of rotation of the drum in normalconditions is that indicated by the arrow 26, and a clearance stop 27,in the known form of an adjustable eccentric, is carried by the anchorplate. For preventing the brake shoes from vibrating about their pivots,a spring 28 is connected between the shoe 4 and a stud 29 secured to theanchor plate so as to hold the shoe 4 on the stop.v

It will be seen that, when the cable is pulled relatively to the casing,so as to twist the cam, the brake shoes are separated; and as the camand actuating lever are supported entirely by the shoes and do notoperate about a fixed pivot, the shoes can adjust themselves so as toapply equal pressures. Y

Other advantages of the invention are that a very neat construction isobtained, as the anchor plate is devoid of the usual boss carrying the Vcam spindle, there is no external lever for twisting the cam and thereis no bearing for 'the cam spindle which frequently causes troublethrough lack of lubrication. The same design of brake can be used foreither steering or non- 295 steering wheels. If the former, the cableflexes outside the brake drum in accordance with the steering movements.

What I claim as my invention and desire to secure by Letters Patent ofthe United States isz- 1. An internal-expanding brake comprising arelatively rotatable drum and support, a pair of brake shoes pivotallyanchored on said sup' port with their free ends adjacent one another,one of said shoes having a recess near its free end, and a floatingactuator supported between said 'free ends, said actuator having an armextending into said recess longitudinally of said recessed shoe. 1.10

CII

2. A shoe brake comprising a brake drum, pivotally-anchored shoes, andan actuator for thrusting said shoes with substantially equal pressuresinto contact with said drum, said actuator being supported solely bysaid shoes and comprising a pair of side-by-side studs and lever meansholding said studs in spaced relation, one of said shoes having a recesspartly to accommodate one of said studs between said shoes, said oneshoe having a further recess partly to ac-.

commodate said lever means.

3,'A shoe brake comprising a brake drum, pivotally-anchoredV shoes, andan actuator for thrusting said shoes with; substantially :equal '5pressures into contact with said drum, said actuator being supportedsolely by said shoes and comprising a pair of side-by-side studs andlever means holding said studs in spaced relation, one

of said shoes having a recess partly to accommodate one of said studsbetween said shoes, said jQne shoe having a. further recess` ,partly toaccommodate said lever means, said further recess Ybeing centrallyk ofvthe width of the zshoe.

f4. A shoe brake comprising brake shoes piv- Qtally-mounted at adjacentends, onepof said ,shoes having a central longitudinal recess at itslfree end,l an actuator `supported solelyyby said shoes between theirfree ends, said actuatorhaving an arm extending into said recesslongitudii, nallyof said recessed-shoe. Y

,5; Ash oe brake comprising brake shoes pivotally-mounted at adjacentends, one of said shoes `having a central longitudinal recess at its freeend, an actuator supported solely by said 11 yshoesfbetween theirfree ends, said actuator hav,-

ing an arm extending in said recess, and means for operating said`arm-extending transversely intosaid recess.

Votally-anchored brake shoes, one of said shoes having a hollow therein,and a oating cam and lever for thrusting said shoes into contact withsaid drum, the free end of said lever being always disposed in saidhollow kand having operating meansconnected to it.

8. In a brake shoe construction, a brake drum, brake shoes movablymounted within the drum, one of said brake shoes having a longitudinalrecess therein, and means for spreading said brake shoes including anarm movably mounted in the recess and extending longitudinally of therecess with its free end in the interior of the shoe. 9. In a brake shoeconstruction, a drum, brake shoes movably mounted in the drum and havingends disposed opposite oneanother, one end being substantially flat andWide in a radial sense, the end of theiother shoe beingnarrow radiallyand having aY cut away portion,f-and actuating means for the shoeshaving two radially separated studs both engaging the wide flat endinnorrnal position, o ne of said studs lying Within the cut away portionand-engaging the end of the other brake shoe, the other stud lying 1beside and out of contact with the cut away end of the shoe.

GEORGE THOMAS SMITH-CLARKE.

